1. Field of the Invention
The present invention relates to a wafer carrier transport vehicle and, more particularly, to a PGTV (personal guided transport vehicle) to be used in an intrabay of a semiconductor fabrication to transport wafer carriers.
2. Description of Related Art
Conventionally, a variety of transport vehicles including floor track type, overhead track type, and trackless computer-controlled type wafer carrier transport vehicles are intensively used to transport wafer carriers in an intrabay of a semiconductor fabrication between a stocker and a load port. There are semiconductor fabrications using personal guided vehicles to transport wafer carriers too.
In recent years, wafers are made greater. A 12 inches wafer carrier weighs over 8 Kgs after loaded with 25 pieces of wafers. Repeatedly carring wafer carriers between the stocker and the load port (or between the load ports) with human power causes the operator to get tired or to be injured easily. In case a wafer carrier falls from the stocker or the load port accidentally during carring, the storage wafers will be damaged.
WIPO Publication #WO00/55074 discloses a PGV (personal guided vehicle). According to this design, the horizontal movement and the vertical movement are independently operated without mutual interlock. A false action may easily occur during operation, causing wafer carriers to fall from the vehicle accidentally. Another drawback of this design is that the horizontal movement and the vertical movement cannot be self-locked. Furthermore, it is difficult to keep the PGV in alignment with the docking flange, resulting in a positioning problem.
Therefore, it is desirable to provide a personal guided transport vehicle that eliminates the aforesaid drawbacks.
The main object of the present invention is to provide a personal guided transport vehicle, which assists the operator to transport wafer carriers, lowering the possibility of occupational injury and improving the manufacturing efficiency. It is another object of the present invention to provide a personal guided transport vehicle, which enables the horizontal motion unit and the vertical motion unit to be interlocked mutually, preventing a false action during operation. It is still another object of the present invention to provide a personal guided transport vehicle, which enables the horizontal motion unit and the vertical motion unit to be independently operated and respectively self-locked. It is still another object of the present invention to provide a personal guided transport vehicle, which can easily be positioned in the docking flange. According to one aspect of the present invention, the personal guided transport vehicle comprises vehicle base frame, a horizontal motion unit, a vertical motion unit, a carrier support unit, and an interlock mechanism. The vehicle base frame has a three-dimensional frame structure composed of a plurality of frame bars, a horizontal table in a middle part thereof, and a plurality of wheels at a bottom side thereof. The horizontal motion unit comprises at least one horizontal rail mounted on the horizontal table, a horizontal slide mounted on the at least one horizontal rail of the horizontal motion unit and adapted to move along the at least one horizontal rail of the horizontal motion unit, a shaft supported on the horizontal slide, and a horizontal operating lever fixedly connected to the shaft of the horizontal motion unit for operation by hand to rotate the shaft of the horizontal motion unit. The vertical motion unit comprises at least one vertical rail fixedly mounted on the horizontal slide, a vertical slide mounted on the at least one vertical rail of the vertical motion unit and adapted to move along the at least one vertical rail of the vertical motion unit, a shaft mounted on the horizontal slide, a vertical operating lever fixedly connected to the shaft of the vertical motion unit for operation by hand to rotate the shaft of the vertical motion unit, and a cam fixedly mounted on the shaft of the vertical motion unit and adapted to move the vertical slide along the at least one vertical rail of the vertical motion unit upon rotation of the shaft of the vertical motion unit. The carrier support unit comprises two horizontal forks disposed at a top side and adapted to carry a wafer carrier, and an upright support disposed at a bottom side and fixedly fastened to the vertical slide. The interlock mechanism is adapted to interlock the shaft of the horizontal motion unit and the shaft of the vertical motion unit. According to another aspect of the present invention, the vertical motion unit further comprises a coupling block fixedly mounted on the shaft thereof, the coupling block having at least one mounting hole. The interlock mechanism comprises a shaft mounted on the horizontal slide, a gear set coupled between the shaft of the horizontal motion unit and the shaft of the interlock mechanism, an actuating block concentrically fixedly mounted on the shaft of the interlock mechanism, a link, the link of the interlock mechanism having a first end eccentrically pivoted to the actuating block and a second end, and a lock pin pivoted to the second end of the link of the interlock mechanism and adapted to engage one of the at least one mounting hole of the coupling block of the vertical motion unit in order to interlock the shaft of the horizontal motion unit and the shaft of the vertical motion unit. According to still another aspect of the present invention, the personal guided transport vehicle further comprises a horizontal self-lock. The horizontal self-lock comprises a mounting block fixedly fastened to the horizontal slide around the shaft of the horizontal motion unit, the mounting block of the horizontal self-lock having at least one recessed positioning point, and a spring plunger connected in parallel to the operating lever of the horizontal motion unit at one side and adapted to engage one of the at least one recessed positioning point of the mounting block of the horizontal self-lock to lock the operation lever of the horizontal motion unit. According to still another aspect of the present invention, the personal guided transport vehicle further comprises a vertical self-lock. The vertical self-lock comprises a mounting block fixedly fastened to the horizontal slide around the shaft of the vertical motion unit, the mounting block of the vertical self-lock having at least one recessed positioning point, and a spring plunger connected in parallel to the operating lever of the vertical motion unit at one side and adapted to engage one of the at least one recessed positioning point of the mounting block of the vertical self-lock to lock the operation lever of the vertical motion unit. According to still another aspect of the present invention, the personal guided transport vehicle further comprises a docking mechanism for positioning on a docking flange. The docking mechanism comprises a pivot axle provided at a front bottom side of the vehicle base frame, a locating plate pivoted to the pivot axle, and a coupling plate pivoted to the pivot axle. The locating plate of the docking mechanism has a middle locating notch adapted to engage a locating pin at a docking flange. The locating notch has a wide front open side. The coupling plate of the docking mechanism has two forwardly extended hooks adapted to hook on a flange of the docking flange. According to still another aspect of the present invention, the vehicle base frame has horizontal guide wheels disposed at the front bottom side thereof and adapted to guide the vehicle base frame into position when loading in a load port, for enabling the docking mechanism to be positioned in the docking flange by means of the operation of a linkage.
Other objects, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.